Q&A ’13: How to troubleshoot hydroprocessing reactor turnarounds

Much advance work must go into organizing a turnaround and catalyst change. Mr. Alexander said that work starts with monitoring reactor conditions and catalytic activity. He noted that any planning worth its salt should commence from 12 to 18 months in advance of the catalyst change.

Mr. Alexander was equal parts expert, teacher, moderator,
cajoler and philosopher as he held court during his
presentation. His folksy charm and willingness to solicit
opinions from the audience at various points during his talk
facilitated one of the best session conversations during this
year's Q&A and Technology Forum.

Planning. Much advance work must go into
organizing a turnaround and catalyst change. Mr. Alexander said
that work starts with monitoring reactor conditions and
catalytic activity. He noted that any planning worth its salt
should commence from 12 to 18 months in advance of the catalyst
change. On the subject of scheduling, Mr. Alexander was frank:
prepare for delays. He said the earlier a refiner can begin
soliciting contractors for maintenance work, the better. "Keep
in mind you aren't the only refinery to be in turnaround when
you are planning this," he said.

Another key aspect to consider is how a refiner plans to
sulfide the catalyst. "If you are going to use preactivation,
you will need more lead time," he noted.

Once a plant's maintenance plan is set, meetings
should immediately start with turnaround groups. "Define
schedule restraints as clearly as possible," Mr. Alexander
recommended. "There could be other units coming down at the
same times. Coordinate with the other engineers and units.
Assign specific tasks to individuals as much as possible.
Evaluate your staffing requirements. You will need extra
engineers for the units since you will have around-the-clock
coverage."

Mr. Alexander is also a strong proponent of staging the
equipment coming onsite. Whether this equipment is cranes,
cleaning equipment or catalyst bins, plant management must
appropriately allocate spacing at the site and not allow work
dates to sneak up.

"We like to do job walks," Mr. Alexander said. He and his
team decide where to locate equipment trailers onsite, and
discus appropriate connection points. He also said it is
essential to develop contingency plans.

Activate. A catalyst will not do anything
until it is activated. Within hydrocarbon and chemical processing,
three techniques are used for activating catalyst. The first is
in-situ sulfiding. This process is the lowest in cost and is
the industry standard. It usually takes 24 to 30 hours for the
sulfiding step to execute. However, there are some negatives
associated with this technique; mainly that the refiner must
bring in sulfur chemicals. H2S levels must also be
monitored.

Presulfurization is the second technique. In this instance,
sulfur is delivered on the catalyst. Such a setup demands a
higher cost than in-situ sulfiding. Another negative is the
potential for exotherms.

The last widely used sulfiding technique on the market is
preactivation, which offers the fastest startup time. The
catalyst is delivered in active form and ready to go, with no
exotherms. One negative to this approach is that the cost is
quite high. With this option, the refiner must also organize
bin rental and budget for more lead time/scheduling.

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